Speedy lathe chuck key

If you're like me there will often be times when you need to put a small diameter item in the chuck to be turned, then shortly afterwards you need to turn something which is much larger. I seem to be forever winding the chuck in and out with the usual T shaped key, and if you're using a large chuck this can be tiring on your wrist after a while.

I've made up this key which has a neat fitting square milled from round bar and welded to one end, and a nice fitting knurled sleeve with a bolt through it as a handle on the other end. It works a treat and makes light and quick work of winding the chuck scroll in and out. When you need to tighten the chuck I suggest you use the you use the T key to make sure the item is properly secured.

You will notice the square end which fits into the chuck has been dabbed with nail polish over the weld. I have several chucks all with different size keys and I've made a speedy key for each chuck and used nail polish of different colours to indicate the like sized keys which fit the same chuck.

Ignore the semi circular holes on the handle near my thumb in the 2nd photo, they just happened to be in the scrap bar I used.

I took a somewhat different approach. When the chuck is mounted I didn't want to have to use one tool to speed the jaw movement, then put it down and pick up the supplied chuck wrench to tighten the jaws.

I mounted a 1" diameter aluminum cylinder to one arm of the chuck wrench. It's held in place by a setscrew bearing on a flat filed on the wrench arm. The top of the cylinder has a hemisphere turned on it.

As shown in the picture below, by putting your palm on the hemisphere and moving your hand in a small horizontal circle you can spin the wrench rapidly. Once the jaws are snug on the work shift your hands to the normal wrench arms and tighten down.

That's not to say that there isn't a use for cranks and other forms of speeders. When I clean the jaws and scroll, I do it on the bench and here a fast way of moving the jaws is very desirable. The solution above doesn't work because, with the chuck horizontal on the bench, the bench top fouls the arms of the chuck wrench.

My first solution was to build a small crank similar to yours (shown upper left in the photo below). It works well but I quickly discovered that the 3/8" socket driver for my electric screwdriver just fit the socket on one of my chuck jaws.

Other of my chucks needed a different size driver so I cobbled up the one shown below the socket driver. Just a chunk of steel with a square of the correct size milled on one end. A cut-down Allen wrench is force-fit in the other end to provide an interface to the electric screwdriver.

Hi Bony,
As I remember it was a discussion about speeding this operation, especially about the security problem, I don't know the working legislation in your country but here in EU if you are not alone to work it's impossible to use a chuck key without security.
The solution with those very usable keys is to put in the center a rod mounted with a spring to expel them when you don't push on it.
I have an old one without spring and it's clearly more practical than the other secured but I've seen a key flying in the workshop too and it's not a good idea for the end of the year to see that again…
Then just an idea for securing a very practical tool.
Have a nice day.
Pierre

I live in Tasmania and I am not aware of any legal requirement in Australia to use a spring loaded chuck key and I very much doubt this is the case. A lathe can be a dangerous tool and there are many many other more serious hazards, such as entanglement, entrapment and blinding. I was always taught to NEVER EVER leave a chuck key in a chuck, and I don't even do on a chuck fitted on a rotary table which remains stationary. And I ALWAYS wear safety glasses when around machinery.

Having said this most of my chuck keys were fitted with springs when they were brand new out of the box, and everyone I know takes the spring off because it's so much easier to use the key without it.

Thanks for mentioning it, for best practice ALL chuck keys should be fitted with a mechanism to prevented them remaining in the chuck.

Bony

Originally Posted by Okapi

Hi Bony,
As I remember it was a discussion about speeding this operation, especially about the security problem, I don't know the working legislation in your country but here in EU if you are not alone to work it's impossible to use a chuck key without security.
The solution with those very usable keys is to put in the center a rod mounted with a spring to expel them when you don't push on it.
I have an old one without spring and it's clearly more practical than the other secured but I've seen a key flying in the workshop too and it's not a good idea for the end of the year to see that again…
Then just an idea for securing a very practical tool.
Have a nice day.
Pierre

Any shop, wood or metal, is filled with opportunities for serious, even deadly, injuries. If you can't develop the mental discipline to avoid these situations you don't belong in the shop.

The spring-loaded chuck key is just one example of the nanny-state mandating a solution to a single problem that makes the general situation worse by creating the impression in the mind of the worker that he is mechanically protected from injury by the state and no longer has to think for himself about what could go wrong.

In an environment where untrained workers are allowed to operate complex machinery, mechanical safety devices like the spring-loaded key or two switches that must both be pressed to operate a punch make sense because the operator isn't expected to evolve his own strategy for completing the job; he's there as an operator, an extension of the machine.

In an environment where the worker is expected to evolve his own methodology for building the part or solving the problem, the only real way to safety is training him to think for himself.

Spot on, any machine is dangerous and respect of that has to be taught at the beginning, however most people who are to use a machine for the first time are naturally cautious and most of the accidents I have been unfortunate to witness have been of the familiarity breeds contempt variety. You cant legislate against stupidity.